Pero luego pensamos en ello, y nos damos cuenta de que los tags no deberían repetirse, probablemente serían strings únicos.

Y Python tiene un tipo de datos especial para conjuntos de elementos únicos, el `set`.

Entonces podemos declarar `tags` como un conjunto de strings:

{* ../../docs_src/body_nested_models/tutorial003_py310.py hl[12] *}

	}
	var nonce [32]byte
	if _, err := io.ReadFull(random, nonce[:]); err != nil {
		logger.CriticalIf(context.Background(), errOutOfEntropy)
	}

	const Context = "object-encryption-key generation"
	mac := hmac.New(sha256.New, extKey)
	mac.Write([]byte(Context))
	mac.Write(nonce[:])
	mac.Sum(key[:0])
	return key
}

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

		Ciphertext: `{"aead":"ChaCha20Poly1305","iv":"JbI+vwvYww1lCb5VpkAFuQ==","nonce":"ARjIjJxBSD541Gz8","bytes":"KCbEc2sA0TLvA7aWTWa23AdccVfJMpOxwgG8hm+4PaNrxYfy1xFWZg2gEenVrOgv"}`,
	},
	{
		KeyID:      "my-key",
		Plaintext:  "UnPWsZgVI+T4L9WGNzFlP1PsP1Z6hn2Fx8ISeZfDGnA=",
		Ciphertext: `{"aead":"ChaCha20Poly1305","iv":"r4+yfiVbVIYR0Z2I9Fq+6g==","nonce":"2YpwGwE59GcVraI3","bytes":"k/svMglOU7/Kgwv73heG38NWW575XLcFp3SaxQHDMjJGYyRI3Fiygu2OeutGPXNL"}`,

##### Figure 1 - Secure Channel construction

```
plaintext   := chunk_0          ||       chunk_1          ||       chunk_2          ||       ...
                 |                         |                         |
                 |                         |                         |
               AEAD <- key, nonce + 0    AEAD <- key, nonce + 1    AEAD <- key, nonce + 2    ...